Cook pasta in salted boiling water according to package directions; drain. Return to pot. Keep warm. Meanwhile, in small skillet heat 1/4 cup olive oil over medium-low heat. Place six basil leaves in hot oil; cook 2 to 3 minutes each side or until crisp (leaves will brown a little). Carefully remove to paper towels to drain. Sprinkle lightly with salt. Cut remaining basil leaves into thin ribbons; set aside.

For sauce, in large skillet sauté leeks with butter over medium heat until tender and lightly browned (about 3 minutes). Sprinkle lightly with salt and white pepper. Remove leeks from skillet; set aside.

If desired, to grill shrimp, thread shrimp onto metal or soaked wooden skewers, leaving 1/4-inch between pieces. Sprinkle shrimp lightly with salt and pepper. Place skewers on rack of charcoal or gas grill over medium heat. Cover; grill 2 to 3 minutes, turning once, or until shrimp are opaque. Remove from skewers; set aside. (Shrimp can be made ahead and chilled.)

With vegetable peeler, cut zucchini and yellow squash lengthwise into thin ribbon slices (stop when you get to the seeds). Place on paper towels; pat dry. Sprinkle lightly with salt and pepper.